A dart generally consists of a body, the leading end of which carries a needle-like point which is to penetrate the dart board and the trailing end of which leads to a flight shaft terminated by a flight. The body is usually thicker and heavier than the flight shaft to facilitate throwing the dart and to position the dart's center of gravity at the desired location along the dart.
Usually the dart body and shaft are separately turned or formed parts which may be threadedly connected together. Some darts also have their tips threadedly connected to the leading end of the dart body. This enables the different parts of the darts to be made of different materials. For example, the dart body may be made of wood or metal and the flight shaft of a relatively lightweight plastic material. The dart point is usually of steel when the dart is to be thrown at a conventional dart board. On the other hand, a dart used with an electronic dart board may have a plastic point.
A dart having a solid body is disadvantaged in that its weight and center of gravity or balance is determined at the time of manufacture. Therefore, a dart which may have satisfactory weight and balance for one player may not suit another player.
To solve this problem, darts have been developed whose overall weight characteristics can be adjusted. For example U.S. Pat. No. 3,957,271 describes a dart to which annular weights may be added to control the overall weight and length characteristics of the dart. On the other hand, U.S. Pat. No. 5,009,433 and British Specification 1 590 954 disclose darts having an internal cavity which may be partially or completely filled with metal balls or particles. In the case of the former dart, the internal weight functions as a moveable ballast which moves from the tail of the dart toward the point upon impact with the dart board to assist in the adherence of the dart to the dartboard.
Such prior adjustable darts have not been entirely satisfactory for a variety of reasons. Some are relatively complicated and expensive to manufacture. Others are composed of several small parts which can become loose and upset the flight characteristics of the darts. Still other prior darts cannot be customized as to dart length.